The invention is directed to electric machine, and more particularly to a method of producing an electric machine rotor or stator from sheet metal blanks.
One method for producing a rotor of an electrical machine from sheet metal blanks in which the sheet-metal blanks, stamped out with a die, are embodied centrosymmetrically is known from German Patent Disclosure DE 32 46 356 A1. The sheet-metal blanks are arranged in the laminated rotor core, if the geometric embodiment of the blanks allows it, arranged in random distribution or at a certain angle relative to the next sheet-metal blank in the circumferential direction. The intent is largely to compensate for the magnetic anisotropy generated by the process of rolling the metal sheets. With asymmetrical sheet-metal blanks, however, this method fails, since the nonrotatability means that the magnetic preferential direction of all the sheet-metal blanks is oriented in the same direction.
The method of the invention with the has the advantage over the prior art that in a single work step, two congruent sheet-metal blanks are created, which depending on the angle of sheet-metal strip rotation have magnetic preferential directions extending differently, so that as a result, when the sheet-metal blanks are stacked in pairs to form a laminated rotor core or laminated stator core, extensive cancellation of the magnetic anisotropy can be achieved. By the multi-ply cutting of the sheet-metal blanks in one cutting operation, that is, using a die, tool costs are also saved, since otherwise two cutting tools would be required. The production costs for a laminated core are also reduced, since per cutting operation, a plurality of sheet-metal blanks can be created simultaneously.